Markets were mulling familiar themes last week. Will a wider U.S. twin deficit change the rules for the dollar and treasuries and is elevated volatility here to stay in equities? Judging by last week, the answer would be: probably and yes. The contemplation over these stories, though, were interrupted by politics. Mr. Trump announced his intention to apply tariffs on steel and aluminium—25% and 10% respectively—and Mrs. May attempted to give clarity on the U.K. government’s Brexit position.* I was unimpressed with both. Before I have a dig at Mr. Trump, I ought to provide an example of someone who supports it. I have great respect for Stephen Jen, but his argument here is like endorsing the idea of a diet by advising someone to eat nothing but kale and carrots for a decade. The analysis of Mr. Trump’s tariffs requires a distinction between the principle and the concrete measures. I concede that China is bending the rules of global trade, but Mr. Trump is stretching the fabrics of macroeconomic policy if he starts imposing tariffs on industrial goods. He is presiding over an economy close to full employment, a low domestic savings rate, and a medium-sized twin deficit. To boot, he is about to let fly with unprecedented fiscal stimulus.

On a headline level, 2018 has started exactly as 2017 finished. Stocks are up, U.S. short term rates are up—but the dollar has traded heavy—and economic data continue to tell a story of a synchronised upturn in global growth. The bears are furious, or perhaps just confused. Hussman recently published a prepper’s guide to a hypervalued market. And value investor extraordinaire—and famed bear—Jeremy Grantham from GMO invokes the “highest-priced markets in US history,” but also proclaims that we’re now in the “melt-up phase” of the bull market. I am all for holding opposing views at the same time, but markets demand a view and a position. So which is it Mr. Grantham? Long, short, or flat? I am not holding my breath for an answer. I have long since left the extremes behind. Picture a spectrum with Hussman and GMO at one end, and the wet-behind-the-ears trader, who have never experienced a sizeable drawdown in Spoos, at the other end. Hint: You want to be somewhere in between.

Separating signal from noise is an important skill in this game, and markets currently are throwing a number of curve balls at investors. What better way to kick off 2018 than by highlighting the ones that matter.

Seven years ago I did a thesis on demographics and capital flows, which informs my thinking on economics and finance to this day. That’s a long time ago, though, so I thought that I would provide an update on one of the key pillars of that work. It starts with ageing. The breadth and speed of population ageing currently sweeping the global economy is unprecedented in human history. It is partly driven by rising life expectancy, which we can crudely hold to be a linear function of economic development. But it is also a result of a complex fertility transition. Two stylised facts should be highlighted at the outset. Firstly, the demographic transition does not end with a homeostatic “equilibrium” of replacement level fertility. Secondly, the decline in fertility seems to be driven by two forces; the quantum effect which operates on a quantity/quality trade-off and the tempo effect, which is the phenomenon of “missing births” as women postpone having their first child. The two are connected in complex ways, that we probably don’t quite understand. My goal here is to understand what is happening to global fertility rates. My sample is the World Bank’s data and their estimates of total fertility rates across countries.

I am tempted to use one of the most tired clichés to describe the state of play in financial markets. In his famous book with the same title, Malcolm Gladwell describes a tipping point as "the moment of critical mass and threshold" at which point the parameters and rules of the game—in a market or environment—change radically. As I peer across markets and economies, I am starting to wonder whether we are getting close to just that. The eye of the storm is quite literally the U.S. where the layers of economic and political uncertainty are now so thick that I am not even sure where to start. The tinfoil hat scenario goes something like this. The devastation of hurricanes Harvey and Irma is worse than feared and become a stagflationary hit—negative supply shock and plunge in demand—but the call for decisive action in Washington and the Eccles building go unheeded. The debt ceiling bites right when the economy needs the flexibility the most and the Fed is caught between a rock and a hard place as inflation soars. Pyongyang uses the confusion to show that it means business by firing a missile towards Alaska.